The present invention relates generally to the field of monitoring and controlling input/output modules or devices for a factory automation system. More particularly, the present invention relates to a system for coupling input/output modules or devices to a web server.
Remote monitoring and control of systems, processes and I/O devices has taken many forms. In the past, dedicated lines were the common form of communication between a control system and a remote location. This type of communication had limited application since the control system was not accessible from multiple locations. Modems have made it possible to access the control system from different locations, but these types of systems are generally restricted to downloading and uploading data files. Providing any type of control function between locations is rather limited in this type of environment. Furthermore, a customized interface is generally required to access the control system by an end user.
With the growth of Internet, and its World Wide Web providing a delivery platform for organizing Internet data through hypertext links, a client server system can be designed that will give each end user the same type of user friendly interface and universal access to services on the Web. The Web is a network of documents called sites or pages stored on server computers throughout the world. Each page typically contains text, multimedia offerings, i.e., graphic images, video, or audio; and hypertext links to other web pages or documents. A browser allows a user to read and interact with the web page. The browser is a graphical software program that sends commands to the Internet Web site and displays whatever information is available on the page. Various browser programs are commercially available from different manufacturers, as is well known.
The Internet network employs methods designed to handle thousands of general purpose computers sharing a single cable, and therefore has no ability to differentiate traffic in terms of its purpose or the criticality of its data. The Internet is no longer a network of computers sharing a single cable, but rather a web of interconnected point to point links involving both general purpose stations and specialized infrastructure components such as routers and firewalls.
Most personal computers or work stations can be used by the end user to connect to the Web through the commercially available browsers. Communication over the Internet and other networks requires one of several available protocols. Protocols such as Internet Protocol (IP) provide for file transfers, electronic mail, and other services. Commercially available programming languages such as Java, along with Hypertext Markup Language (HTML), are used in designing layouts and graphics for a web site or page and have extended Internet technology such that a web site can be used for dynamic applications, e.g. applets, that can be downloaded and run by the end user. These applets are interpreted and run within a Web browser and have been generally restricted to word processing and similar uses. Downloading and running applets can be slow in comparison to other types of compiled languages. Security rules imposed on a browser and enforced by the underlying JAVA language prevent applets from obtaining certain data from any other device other than the Web server itself.
Programmable logic controllers (PLCs) are widely used in industry and process control. Many manufacturers provide factory automation information using Microsoft Windows and other types of communication networking environments. These networks are usually slow, not universally accessible, and are limited to monitoring and data exchange. Specialized industrial networks using proprietary fieldbus alternatives can be very expensive. Conversion products are required to allow information carried over those networks to be visible on a general purpose network. There are significant installation and other deployment costs associated with the existence of such intermediate devices. Firewalls between the Web server and the application are designed to solve problems of security and are not designed for high performance.
One type of interface to a programmable logic controller is disclosed in U.S. Pat. No. 5,805,442 to Crater, et al. This patent provides one or more controllers each equipped to perform a control function and to gather data (ordinarily from sensors) relevant to the control function. Each controller contains computer storage means, such as computer memory, for storing the relevant data and instructions, associated with the data, for causing a remote computer to generate a visual display incorporating the data in a predetermined format. The additional time required to transfer data through a programmable logic controller to the monitoring PC decreases the value of the information being monitored. In addition, the monitoring and control of the system""s input/output devices by the remote PC is available only through the use of a programmable logic controller positioned between the monitoring PC and the devices. The real-time delay associated with the integrated PLC contributes to increased network communication traffic and slower updates of network information. Direct connection to the I/O device is beneficial for maintenance, repair, debugging and diagnosing problems, particularly during the installation of factory automation systems and machines.
It would be desirable to develop an automation control system whereby a user could use general purpose networks, such as the Internet and specialized industrial networks, directly connected to input/output devices for remote monitoring and control of input/output modules or devices.
This invention is designed to solve these and other problems.
Accordingly, the principal object of the present invention is to provide an interface between an industrial control system and a Web browser coupled to a network such as the Internet.
Another object of the present invention is to provide remote access through a web browser to information and data contained in an input/output (I/O) device.
In the preferred embodiment of the invention, the invention allows for easy access over a commercial network such as the Internet to information within at least one input/output device. Access can be made locally or worldwide using a commercial Web browser. The invention is comprised of a control system of essential elements including, but not limited to a Web interface, a local network, and a network interface to at least one input/output device. The Web interface runs Web pages from an Ethernet board coupled directly to the input/output back plane and includes a hypertext transfer protocol (HTTP) interpreter, an input/output module back plane driver, a Transmission Control Protocol/Internet Protocol (TCP/IP) stack, and an Ethernet board kernel. The Web interface provides access to the input/output device back plane by a user at a remote location through the Internet. The interface translates the industry standard Ethernet, TCP/IP and HTTP protocols used on the Internet into data recognizable to the input/output device. Using this interface, the user can retrieve all pertinent data regarding the operation of the input/output device, including input/output device configuration, input/output status, operating statistics, diagnostics, and distributed input/output configurations. Updates to operating software can also be downloaded through the Internet access.
Other features and advantages of the invention, which are believed to be novel and nonobvious, will be apparent from the following specification taken in conjunction with the accompanying drawings in which there is shown a preferred embodiment of the invention. Reference is made to the claims for interpreting the full scope of the invention which is not necessarily represented by such embodiment.